Various proposals have recently been made on techniques for displaying a stereoscopic image as a result of the progress of optical technologies. One of such techniques is two-glass type three-dimensional viewers such as IMAX THEATER (trademark) capable of presenting stereoscopic display to a user who wears dedicated eyeglasses to see an image formed by an image for the left eye and an image for the right eye in an overlapping relationship. This apparatus can present stereoscopic display in the form of a stereogram utilizing parallax between left and right eyes.
Stereoscopic display is also performed with holography utilizing coherent light from a laser or the like. This technique is to display a stereoscopic image by forming a hologram on a dry plate or the like using object light and reference light in advance and by irradiating the hologram with the original reference light to obtain reproduction light.
Further, there are lens plate three-dimensional image display techniques represented by the so-called IP (integral photography) method. There is a proposal made by Lippmann in which a photographic dry plate is provided on a focal surface of a lens plate called “fly-eye lens” constituted by a multiplicity of small convex lenses; object light is exposed through the lens plate to record a multiplicity of small object images on the photographic dry plate; and the photographic dry plate is thereafter developed, placed in exactly the same position as its initial position and irradiated with light on the back surface thereof.
Among the above techniques, the above-described stereoscopic viewers are inconvenient for a viewer because he or she must wear dedicated eyeglasses and are not suitable for observation for a long time because they present unnatural images which are likely to give fatigue. In order to solve this problem, stereoscopic televisions have recently been proposed which do not require any dedicated eyeglasses. However, techniques for stereoscopic views of this type only present pseudo-stereoscopic display utilizing parallax between left and right eyes and do not allow three-dimensional display in a true sense. Therefore, although an image can be represented with a stereoscopic sense in the horizontal direction of a screen, it can not be represented with a stereoscopic sense in the vertical direction and, for example, can not be viewed by a person who is lying down. Further, since those are techniques utilizing parallax, a change of a view point only results in a view of the same image with a stereographic sense (a sense of depth), and a side of an object will not appear even if the viewer moves the head to look at the object from left and right sides thereof.
The above-described technique for presenting stereoscopic display utilizing holography involves a large scale apparatus at a high manufacturing cost because of the requirement for coherent light from a laser or the like and also results in a reduction of image quality attributable to speckle interference patterns which are characteristic of lasers. Further, holography is suitable for still images but unsuitable for three-dimensional display of dynamic images because it presents stereoscopic display of an object utilizing a hologram formed on a photographic dry plate in advance. This equally applies to the above-described IP method in that it is unsuitable for dynamic images because it involves a step of recording a multiplicity of small object images on a photographic dry plate in advance.
As described above, it has been difficult to provide televisions and very large displays installed in the street, stadiums or the like capable of presenting stereoscopic dynamic images in a true sense.